Flash Lamp Wafer Heating With In-Situ Crack Detection
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Solution Overview
Problem
Current flash lamp annealing techniques for semiconductor wafers face challenges in detecting cracks during the rapid thermal expansion process, leading to potential wafer deformation and cracking, which complicates the manufacturing process and requires additional steps for detection and chamber cleaning.
Innovation Solution
A heat treatment method and apparatus that irradiate a substrate with a flash of light, measuring the temperature profile of the substrate's front surface using a radiation thermometer and analyzing it to detect cracks by determining if the average value or standard deviation of the temperature profile falls outside predetermined ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If flash lamp annealing is used to rapidly heat the substrate, then heating speed and impurity activation efficiency are improved, but wafer deformation and cracking occur due to abrupt thermal expansion
Solution Approach 1:
The patent performs preliminary heating using halogen lamps before flash lamp annealing to gradually increase the substrate temperature. This preliminary action reduces the temperature differential between the front and back surfaces, preventing abrupt thermal expansion and subsequent wafer cracking while maintaining the high heating speed benefit of flash lamp annealing
Solution Approach 2:
The patent introduces a cushioning heating phase using halogen lamps that activates before the flash lamp annealing. This cushioning phase creates a thermal buffer by pre-heating the substrate, particularly the back surface, which cushions against the sudden thermal shock from flash lamp irradiation and prevents wafer deformation
2Ease of operation
If crack detection is performed after chamber transfer inlet-outlet opening, then detection timing is simplified, but particle contamination occurs from cracked wafers scattering outside the chamber
Solution Approach 1:
The patent performs crack detection using a radiation thermometer immediately after flash lamp annealing while the chamber remains closed. This preliminary detection occurs before the transfer inlet-outlet is opened, allowing identification and removal of cracked wafers before they can scatter particles outside the chamber, thus preventing contamination while maintaining operational simplicity
Solution Approach 2:
The patent uses a radiation thermometer as an intermediary detection device that can measure wafer temperature and detect cracks through the chamber window without requiring chamber opening. This intermediary measurement system enables crack detection to occur before chamber access, preventing particle contamination while maintaining ease of operation
3Reliability
If additional detection hardware is added to the chamber, then crack detection capability is improved, but device complexity increases
Solution Approach 1:
The patent employs a radiation thermometer that serves multiple functions: it measures the substrate temperature during flash lamp annealing and simultaneously detects cracks by analyzing temperature distribution anomalies. This multi-functionality enables crack detection capability improvement without adding separate dedicated detection hardware, thus avoiding increased device complexity
Solution Approach 2:
The radiation thermometer utilizes the thermal radiation already present during flash lamp annealing for its primary temperature measurement function. By analyzing the same thermal radiation data for temperature distribution patterns, the system enables crack detection as a self-service capability of the existing temperature measurement system, eliminating the need for additional detection hardware
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for reliable crack detection during the flash lamp annealing process with improved accuracy, preventing wafer deformation and enhancing the manufacturing efficiency by integrating crack detection directly into the treatment process without additional hardware or complex processes.
Implementation Method 1
irradiating a front surface of a substrate with a flash of light from a flash lamp... temperature of the front surface of the substrate rapidly rises
Implementation Method 2
measuring temperature of the front surface of the substrate... using a radiation thermometer
Data Source
AI summary
A front surface of a semiconductor wafer is rapidly heated by irradiation of a flash of light. Temperature of the front surface of the semiconductor wafer is measured at predetermined intervals after the irradiation of the flash of light, and is sequentially accumulated to acquire a temperature profile. From the temperature profile, an average value and a standard deviation are each calculated as a characteristic value. It is determined that the semiconductor wafer is cracked when an average value of the temperature profile deviates from the range of ±5σ from a total average of temperature profiles of a plurality of semiconductor wafers or when a standard deviation of the temperature profile deviates from the range of 5σ from the total average thereof of the plurality of semiconductor wafers.